It is known that benzylamine-type trifluoromethanesulfonamide derivatives such as N-benzyltrifluoromethanesulfonamide and the like and trifluoromethanesulfonamide derivatives having a condensed heterocyclic ring structure have herbicidal activity so that they are used as a herbicide.
These compounds, however, have no sufficiently high herbicidal activity against troublesome weeds and common weeds in upland field and, in an addition, have a problem in respect of the phytotoxicity to crops.
A first object of the present invention is to provide a herbicide containing a novel trifluoromethanesulfonamide derivative as the active ingredient having, by solving the problem of the phytotoxicity to crops, sufficiently high herbicidal activity against weeds including purple nutsedge, i.e. Cyperus rotundus, and safety for crops in an upland field such as soybean, cotton, maize and the like.
A second object of the present invention is to provide the novel trifluoromethanesulfonamide derivative used as the active ingredient of the above mentioned herbicide and an efficient method for the preparation thereof.